Ink jet recording is carried out in such a manner that minute ink droplets are allowed to jet utilizing various working principles, and to allow said ink droplets to adhere onto a recording material so that images as well as text are recorded. Ink jet recording exhibits advantages of relatively high speed, low noise, and ease of multicolor printing.
Further, being based on the recent technical progress, pigment ink, comprising pigments, which exhibit excellent lightfastness, a colorant, has received increasing attention as ink for application requiring images with excellent lightfastness.
Pigments are not soluble in solvents. As a result, pigments are dispersed into solvents and are employed in ink in the form of a dispersed state. Therefore, even when the molecules on the surface of dispersed pigment particles results in photochemical decomposition, any new pigment molecular layer under the decomposed layer is exposed. As a result, a decrease in apparent density is minimized. Therefore, said pigment ink is characterized in that excellent image retention properties are achieved.
However, said pigment ink has caused problems in that after image fixing, it is difficult to create high gloss images due to effects of scattered light, as well as reflected light caused by said pigment particles.
Japanese Patent Publication Open to Public Inspection No. 11-208097 discloses a technique in which recording is carried out onto a recording material having the uppermost layer comprised of a thermoplastic resinous layer, employing pigment ink comprising no dispersing agents, and thereafter, pigment particles are allowed to migrate into said thermoplastic resinous layer. The inventors of the present invention studied said patent and found the following. After said pigment ink was ejected onto said recording material, said pigment particles remained on the surface of said thermoplastic resinous layer, while solvent components of said pigment ink were absorbed by each layer constituting said recording material. Subsequently, by allowing said pigment particles to migrate into said thermoplastic resinous layer, protrusion of printed portion with respect to the non-printed portion, which was specific to said pigment ink, was minimized, whereby consistent gloss enhancing effects were obtained due to enhancement of smoothness.
However, when said pigment particles are not completely buried into said thermoplastic resinous layer, imagewise unevenness is created in the printed portion as well as in the non-printed portion, whereby a gloss difference between them tends to occur. On the other hand, when said pigment particles are completely buried, any gloss difference between the printed portion and the non-printed portion is eliminated. However, other problems occur in which desired glossiness characteristics are not obtained.
Further, Japanese Patent Publication Open to Public Inspection No. 2000-103044 discloses a heating roller and a pressure roller, which is provided so as to face said heating roller, as a drying means to dry ink ejected onto a recording material. By employing said technique, protruding ink is assuredly smoothened and ink results in more desired gloss than that created by conventional image forming apparatus. However, problems have occurred in which the resultant gloss does not reach the desired level and a peeling ability of said heating roller from pigment ink is insufficient.
Still further, Japanese Patent Publication Open to Public Inspection No. 2000-1512 discloses an image output apparatus which is provided with an image forming section which forms images on a printing material, employing ink, and a pressure section which applies pressure to said printing material, on which images are formed, employing said image forming section, in order to output high gloss images without using special recording sheets and ink.
Said patent also discloses a fixing apparatus utilizing silicone rubber, coated with fluorine and is arranged in said image output apparatus. However, problems have occurred in which the resultant images do not exhibit sufficient gloss and peeling ability of the roller from the pigment ink was insufficient.
In image processing apparatuses such as electrophotographic copiers and electrophotographic printers, which utilize electrophotographic processes, it is necessary that toner images, which have been transferred to transferring materials such as copy paper sheets, are fixed. Widely employed as said toner image fixing method is one in which a paper sheet is allowed to pass between a rotating heating roller and a pressure roller in contact with each other so that the toner image on said copy paper sheet is thermally fused.
However, said method has caused the following problems. Due to the relatively short contact length of said copy paper sheet with said fixing roller depending on its radius of curvature, said copy paper sheet is separated from said fixing roller after a relatively short contact time with said fixing roller. Specifically, full color toner of a relatively low meting point tends to result in offsetting and the surface of said toner is roughened. As a result, the resultant toner images do not result in a mirror surface, whereby it is difficult to prepare images of the desired gloss.
Further, heretofore, in order to minimize offsetting, silicone oil has been applied onto the surface of the fixing roller. However, problems have occurred in which, since it becomes necessary to provide a device to apply said silicone oil, the resultant apparatus becomes more complex. In addition, when an original document is copied onto OHP film, it has been noted that said film is stained with said silicone oil.
Still further, Japanese Patent Publication Open to Public Inspection No. 5-265337 discloses that in a fixing belt comprising a base material having on its surface a surface layer, said belt is characterized in that said surface layer is comprised of a silicone resin.
Said fixing belt is effective to enhance the glossiness of full color toner images, while it does not effectively enhance the glossiness of ink jet recording images to the desired level. Further, problems have occurred in which the surface layer on said fixing belt tends to result in layer peeling.